<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src = "./jquery.min.js"></script>
    <style>
        div{
            height: 400px;
            width:600px;
            background-color: pink;
        }
    </style>
</head>
<body>
    <div>演示内容</div>

    <script>
        $(function(){
            console.log($("div").css("height"));
            $("div").css("height","200px");
            $("div").css({
                "font-size":"40px",
                "font-family":"宋体",
                "color":"#fff",
            })
        })
    </script>
</body>
</html>